[PATCH] per-task-delay-accounting: sync block I/O and swapin delay collection

Unlike earlier iterations of the delay accounting patches, now delays are only
collected for the actual I/O waits rather than try and cover the delays seen
in I/O submission paths.

Account separately for block I/O delays incurred as a result of swapin page
faults whose frequency can be affected by the task/process' rss limit.  Hence
swapin delays can act as feedback for rss limit changes independent of I/O
priority changes.

Signed-off-by: Shailabh Nagar <nagar@watson.ibm.com>
Signed-off-by: Balbir Singh <balbir@in.ibm.com>
Cc: Jes Sorensen <jes@sgi.com>
Cc: Peter Chubb <peterc@gelato.unsw.edu.au>
Cc: Erich Focht <efocht@ess.nec.de>
Cc: Levent Serinol <lserinol@gmail.com>
Cc: Jay Lan <jlan@engr.sgi.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>

1 files changed, 4 insertions, 0 deletions

diff --git a/mm/memory.c b/mm/memory.c
index de8bc85dc8f3..109e9866237e 100644
--- a/mm/memory.c
+++ b/mm/memory.c
@@ -47,6 +47,7 @@
 #include <linux/pagemap.h>
 #include <linux/rmap.h>
 #include <linux/module.h>
+#include <linux/delayacct.h>
 #include <linux/init.h>
 
 #include <asm/pgalloc.h>
@@ -1934,6 +1935,7 @@ static int do_swap_page(struct mm_struct *mm, struct vm_area_struct *vma,
                 migration_entry_wait(mm, pmd, address);
                 goto out;
         }
+        delayacct_set_flag(DELAYACCT_PF_SWAPIN);
         page = lookup_swap_cache(entry);
         if (!page) {
                 swapin_readahead(entry, address, vma);
@@ -1946,6 +1948,7 @@ static int do_swap_page(struct mm_struct *mm, struct vm_area_struct *vma,
                         page_table = pte_offset_map_lock(mm, pmd, address, &ptl);
                         if (likely(pte_same(*page_table, orig_pte)))
                                 ret = VM_FAULT_OOM;
+                        delayacct_clear_flag(DELAYACCT_PF_SWAPIN);
                         goto unlock;
                 }
 
@@ -1955,6 +1958,7 @@ static int do_swap_page(struct mm_struct *mm, struct vm_area_struct *vma,
                 grab_swap_token();
         }
 
+        delayacct_clear_flag(DELAYACCT_PF_SWAPIN);
         mark_page_accessed(page);
         lock_page(page);